where we use notation from the book by Hardy and Wright [1]}, \(d(k)\) , which denotes the number of divisors of integer \(k\) 
including 1 and \(k\) . According to Dirichlet (see [1]}),
\(\sum \limits _{k=1}^{n}d(k)=n\ln (n)+(2\gamma -1)n+O(n^{\theta }),\qquad \theta =\frac{1}{2},\) 
